1. Field of the Invention
This invention is in the field of fluorine-doped tin-oxide coatings on glass; more particularly, the present invention is in the field of pretreating methods for gaseous treatment of substrates for the production of uniform coatings at a high deposition rate, wherein the treated substrate has a reduced bulk resistivity and emissivity.
2. Description of the Prior Art
Brown, in U.S. Pat. No. 4,721,632, describes a method for improving the conductivity and lowering the emissivity of a fluorine-doped tin-oxide film on a glass sheet. The method disclosed involves pretreating the hot glass with a spray solution of ammonium fluoride in either water or a mixture of methanol and water. Spray pretreatment of other fluorine compounds in a suitable solvent is also mentioned. However, spraying hot glass with these solutions results in excessive cooling of the glass, which reduces the deposition rate and can reduce the conductivity of the fluorine-doped tin-oxide coatings. Furthermore, uneven cooling of continuous glass ribbons prevents the tin-oxide coatings from covering the entire glass surface in a uniform fashion.
Accordingly, an object of the present invention is to provide a method and composition for increasing the deposition rate of fluorine-doped tin-oxide coatings on glass substrates.
Another object herein is to provide fluorine-doped tin-oxide coatings which exhibit low bulk resistivities and emissivities.